The invention relates to a device for writing information blocks in a track pattern on a record carrier of a writable type, which device is provided with a write unit for writing areas of the record carrier via (i.e. by using) a beam of electromagnetic radiation with marks representing the information blocks, and positioning means for positioning the write unit based on a track structure which defines the track pattern on the record carrier.
The invention also relates to a writable record carrier having a track pattern for writing information blocks, and a track structure which defines the track pattern.
The invention also relates to a method of writing information blocks in a track pattern on a record carrier of the writable type. Marks representing the information blocks are written in areas of the record carrier via a write unit and a beam of electromagnetic radiation. The write unit is positioned based on a track structure which defines the track pattern.
The invention also relates to a reading device for reading information blocks represented by optically readable marks in a track pattern on a record carrier. The device is provided with a read unit for reading the marks via a beam of electromagnetic radiation, and apparatus for positioning the read unit on the basis of the marks.
A writing device, a method and a record carrier of the type described in the opening paragraph for writing information blocks are known from U.S. Pat. No. 4,901,300 (PHN 12.398). In the system described in that document, information blocks are written in a track pattern on the record carrier and represented by optically readable marks. The record carrier has a track structure in the form of a wobbling pregroove with a varying frequency which represents position information. The writing device has a write head for scanning the record carrier via a beam of electromagnetic radiation. The tracking signals being derived from reflected radiation, and apparatus for positioning the write head during scanning based on the position information. During scanning, a modulation in the tracking signals is produced by the wobble. This modulation includes the position information encoded therein, indicating the absolute position in the track with respect to the starting point of the area intended for information. The information blocks are written on the record carrier at a desired position in conformity with their address, while, if necessary, the write head is positioned via a jump to another radial position in the track on the basis of the position information. A record carrier may be partly written and then includes written areas in which marks are present, and unwritten areas in which only the track structure is present. Reading devices are known which derive the tracking signals and/or position information from the marks. Those skilled in the art are directed to EP 0 328 240 regarding successive formatting. The above citations are hereby incorporated herein in whole by reference the inventors recognized that no position information can be generated in unwritten areas, so that a partly written record carrier is not reliably readable.